Re: [PATCH] sh_eth: ensure pm_runtime cannot suspend the device during init

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Ben,

On Monday 17 March 2014 13:36:33 Ben Dooks wrote:

[snip]

>  From pm_runtime.h:
> 
> static inline int pm_runtime_get_sync(struct device *dev)
> {
> 	return __pm_runtime_resume(dev, RPM_GET_PUT);
> }
> 
> static inline int pm_request_resume(struct device *dev)
> {
> 	return __pm_runtime_resume(dev, RPM_ASYNC);
> }
> 
> So it looks like pm_runtime_resume() does not protect against the
> possibility that something else may re-suspend the device.

Correct.

> I have yet to ascertain how this ends up happening with device probe, it
> seems to be very dependant on the code.

We might be doing something wrong in the driver from a runtime PM point of 
view that leads to the device being suspended. I'd like to catch that instead 
of hiding it by a pm_runtime_get_sync() call. If it turns out that we're not 
doing anything wrong then replacing pm_runtime_resume() with 
pm_runtime_get_sync() would of course be fine.

-- 
Regards,

Laurent Pinchart